Pegasus shutting down for no reason

I have a Pegasus2 R8 running in raid 6 connected to my Imac pro. Untill today everything was running fine, but from today in the morning, the Pegasus keeps shutting down midwork without any reason, as if you pulled the plug on it (no shut down like a regular one).

When hitting the power button it switches on again, but after a while again it just switches of. The time intervalls are allways different, sometimes 12min sometimes 20. Checking the utility i can not find anything wrong, everything is green and also the temperature read outs are fine and in limits.

Did anyone experience this problem alreadyand may be able to help?

The only message i can find in the Utility is "last shutdown was abnormal".